The objective of the proposed research is to attain a detailed understanding of the reactions catalyzed by cytochrome c peroxidase. The investigation is subdivided into two areas. The first area is concerned with the question of what factors are involved in making a heme protein a good peroxidase. The reactivity of the heme site will be investigated with emphasis placed on elucidating the involvement of particular amino acids in the protein. The second area is concerned with the mechanism of electron transfer from oxidizable substrates, in particular the natural substrate ferrocytochrome c, to the oxidized enzyme intermediates. Studies are designed to determine whether complex formation between substrate and enzyme is required for electron transfer, the possibility of multiple electron transfer pathways, the involvement of amino acid residues in the electron transfer pathway, and the effect of substrate redox potential and charge. BIBLIOGRAPHIC REFERENCES: J. E. Erman and T. Yonetani (1975), Biochim, Biophys. Acta 393, 343-349. "The Oxidation of Cytochrome c Peroxidase by Hydrogen Peroxide. Characterization of Products." J. E. Erman and T. Yonetani (1975), Biochim. Biophys. Acta 393, 350-357. "A Kinetic Study of the Endogenous Reduction of the Oxidized Sites in the Primary Cytochrome c Peroxidase-Hydrogen Peroxide Compound."